This invention relates to an annular seal which is secured in a member in a manner to form a fluid tight joint between the seal and the member. More particularly the invention relates to a tube sheet member and an annular seal for a tube-type heat exchanger that is to be used in caustic environments. The heat exchanger tubes are positioned in the opening of the annular seal which are positioned in the tube sheet member.
Heat exchangers have been used for many years to recover heat from various industrial processes. In particular, tube-type heat exchangers have been frequently used as the mechanism to recover heat from industrial processes. A tube-type heat exchanger has a tube sheet with a plurality of apertures located therein. A heat exchanger tube is then inserted into and supported by the apertures in the tube sheet. Normally, a seal is positioned in the aperture in the tube sheet to form a fluid tight seal between the tube sheet and the heat exchanger tube. Usually, the tube sheet and the heat exchanger tube are formed of metal or other similar material having good thermal characteristics for transferring heat.
In operation hot fluids from an industrial process pass through the heat exchanger and come into contact with the heat exchanger tubes. The hot fluids from the industrial process heats the fluid in the heat exchanger tubes and allows a portion of the heat from the industrial process to be recovered.
In many industrial applications the hot fluid from the industrial process is extremely caustic. The caustic nature of the hot fluid severely limits the applications where heat exchangers can be used to extract heat that is otherwise normally lost.
Attempts have been made to develope a tube-type heat exchanger that can operate in such caustic environments to expand the applications where heat can be recovered from hot fluids produced by industrial processes. However, it is extremely difficult to provide a seal for the heat exchanger tubes that can accommodate expansion and contraction of the tube without leakage of the caustic fluids. It is also difficult to form a seal or joint between the annular seals for the heat exchanger tubes and the aperture of the tube sheet. If fluid leaks between the seal and the aperture in the tube sheet the caustic fluid can damage areas of the heat exchanger that are not designed to handle this caustic material.
In prior art heat exchangers a liner that can resist the caustic fluids is positioned on the surface of the tube sheet. The liner protects the metal tube sheet from the caustic fluids. However, it is difficult to form a fluid tight seal or joint between the liner and the seals for the heat exchanger tubes. It is also difficult to form a fluid tight seal or joint between the liner and the apertures in the tube sheet. Frequently, when a liner is used there is leakage or seepage between the liner and the annular seals or the apertures in the tube sheet. Such leakage can cause serious damage to the components of the heat exchanger.
Accordingly, it is desirable to have a seal for the tubes used in a tube-type heat exchanger to prevent the leakage of caustic material between the seal and the aperture in the tube sheet and that can also form a fluid tight seal with the heat exchanger tube.